1. Field of the Invention
The present invention relates to an image processing device, an imaging device, an image processing method, and a program, and in particular, to an image processing device, an imaging device, an image processing method, and a program which perform a restoration process based on a point spread function.
2. Description of the Related Art
In an object image photographed through an imaging optical system, a so-called point spread phenomenon in which a point object has minute spread due to the influence of diffraction, aberration, or the like caused by the imaging optical system may be observed. A function representing a response to a point light source of an optical system is called a point spread function (PSF), and is known as a parameter responsible for resolution deterioration (blurring) of a photographic image.
The photographic image deteriorated in image quality due to the point spread phenomenon can be recovered in image quality through a restoration process (point image restoration process) based on the PSF. The point image restoration process is a process in which a deterioration characteristic (point image characteristic) caused by aberration or the like of a lens (optical system) is determined in advance, and point spread of the photographic image is cancelled through an image process using a restoration filter according to the point image characteristic.
While improvement of image quality is basically expected if the restoration process is performed, the restoration process may cause deterioration of image quality. In order to cope with this case, various methods have been suggested.
For example, JP2009-171341A discloses a shake correction device which suppresses the execution of an unnecessary shake correction process. This correction device estimates uniformity of shakes included in an image to be corrected from two images for estimation and performs the shake correction process based on uniformity using a PSF.
In addition, if a restoration process is performed for a saturated pixel or a defocus region, image quality may be deteriorated, and various methods which cope with image quality deterioration due to the restoration process for the saturated pixel or the defocus region have been suggested.
For example, JP2010-283527A discloses an image processing device which suppresses noise occurring when a restoration process is performed for an overexposed white region, that is, a region where a saturated pixel is included, and reduces image quality deterioration due to an imaging optical system. This image processing device performs gain adjustment based on correction of an exposure of imaging data subjected to a recovery process.
JP2012-65114A discloses a technique which sets a defocus position and performs blur correction using a PSF with reference to information relating to the defocus position.
In addition, various methods which perform a point image restoration process for a moving image have been suggested.
For example, JP2008-11492A discloses an imaging device which performs a restoration process using a PSF for a moving image. This imaging device uses a first filter when an image restoration process is performed for a still image, and uses a second filter when an image restoration process is performed for a moving image.